I am supposed to fly on 817 on 3/12, and when I checked in tonight, flight status showed the flight delayed 1 hr 45 mins already . How would they know 24 hours in advance? There isn't any weather in Denver. I tried calling the 800#, but the hold time was 25 mins

It could be anything you have said, however, because it was posted so far in advance my guess is that there is some MX work being done somewhere in the fleet. Either the aircraft going to MCI is running late because it was/is scheduled to have work done earlier in the day or they are short on a/c due to MX and to minimize delays across the fleet they have chosen to delay specific flights as a result of unplanned a/c swaps and there is no realistic way to reduce the delay any further.

In April, F9 called me to tell me 2 days in advance that a flight was canceled due to weather. The snow was already falling when they called and the storm lasted three days. They rebooked me in time to get me where I needed to go on time and let me change the return so I would be there longer than 24 hours. No charge.